The four tumor suppressor genes LKBI (gene name STK11), TSCl, TSC2, and PTEN are known to be involved in a wide variety of human cancers, as well as causing human genetic disorders with a high frequency of specific neoplasms. Although drug therapies targeting the affected downstream pathways from the loss of these genes are at various stages of clinical development, including mTORCI inhibitors, clinical experience thus far suggests that in many instances such therapies have limited therapeutic potential in vivo. In this project, we propose a series of studies to examine the effects of loss of each of these four genes in human cancer and in genetically engineered mouse (GEM) models, to develop specific therapies. We will pursue the following specific aims in this proposal. First, we will perform a comparative analysis of human cancer cell lines with loss of TSCl vs. TSC2 vs. LKBI vs. PTEN to identify common and differential effects, and compensatory pathways through transcriptional, proteomic, and metabolomic profiles. Second, we will analyze GEM lung and bladder cancers with Tscl vs. Lkbl vs. Pten loss through similar studies. Third, we will perform a Global shRNA (synthetic lethal) screen to identify critical growth targets in GEM cancer primary cultures with Tscl vs. Lkbl vs. Pten loss. Finally, using information gathered from Aims 1 through 3, we will assess potential drug therapies in the GEM models involving these genes. Thus, we will use integrated approaches to identify critical pathways and therapeutic targets in tumors that have LKBI, TSC1/2, or PTEN loss.